GB2114360A

GB2114360A - Fuel transfer manipulator for liquid metal nuclear reactors

Info

Publication number: GB2114360A
Application number: GB08300979A
Authority: GB
Inventors: Robert Harold Sturges
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1982-01-29
Filing date: 1983-01-14
Publication date: 1983-08-17
Also published as: FR2520917B1; JPS58132697A; DE3302711A1; GB8300979D0; US4485067A; GB2114360B; FR2520917A1

Description

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SPECIFICATION

Fuel transfer manipulator for liquid metal nuclear reactors

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This invention relates to a fuel transfer manipulator for liquid metal cooled fast breeder nuclear reactors (LMFBR). The function of the manipulator is to transfer fuel assemblies from a fuel chute arising 10 from the reactor vessel to and from a fuel chute arising from a fuel storage pit to facilitate passage of fuel assemblies therebetween during reactor refueling operations.

The fuel assemblies of LMFBRs are immersed in a 15 liquid metal coolant, usually liquid sodium, which can burn if exposed to environmental oxygen. Consequently, the systems for removing and replacing the fuel assemblies from the reactor must do so while maintaining the assembly in a sealed and 20 protected environment. The usual method is to hoist the assemblies to and from the nuclear reactor vessel and to and from the fuel storage pit via two fuel chutes. The chutes terminate at one end in a transfer chamber where the fuel assembly must be 25 transferred from one chute to the other. The transfer chamber is normally filled with an inert gas such as Argon. Because the transfer chamber is open to the reactor and to the fuel storage pit during fuel transfers, the transfer chamber is considered to be a 30 high radiation and high temperature area to which human access is restricted.

The transfer chamber must be a small size because of the gaseous inerting requirement and because of space limitations imposed by the proxim-35 ity of other equipment.

The transfer manipulator might be a hoist mounted on a bridge trolley, but this solution does not easily match the required motion because the lifting of the hoist must be remotely coordinated 40 with trolley movement. The manipulator might be a pendulum mounted hoist but this solution would require a tall structure for which there is insufficient space in the reactor containment.

It is therefore the principal of the present invention 45 to provide a transfer manipulator which is simple in operation and construction, suitable for long term use in high temperature, high radiation areas, and small in size.

With this object in view, the present invention 50 resides in a fuel assembly transfer manipulator for transferring fuel assemblies between upwardly open fuel chutes which are inclined relative to each other, said manipulator comprising a hoist box with hoisting means supported above said fuel chutes and 55 having a downwardly projecting hoist tube supported for alignment with said fuel chutes for transforming fuel elements therebetween, characterized in that said hoist box is supported by pivot beams having their low ends pivotally supported on 60 a base and their top ends linked to said hoist box, said pivot links being non-parallel and arranged at such an angle that said hoist tube is in alignment with, and in juxtaposition to, said fuel chutes at opposite pivot positions of said beams and that 65 means are provided for controlling pivoting of said beams.

With this arrangement the hoist is shiftable between two extreme positions which correspond to respective alignment configurations between the hoist and a reactor vessel fuel chute and between the hoist and a fuel pit fuel chute.

The invention will become more readily apparent from the following description of a preferred embodiment thereof shown, by way of example only, in the accompanying drawings, wherein:

Figure 1 is a schematic of the shifting beam carriage;

Figure 2 is a schematic of the shifting beam carriage showing three positions;

Figure 3 is a plan view of the shifting beam carriage; and

Figure 4 is a profile view of the shifting beam carriage.

In Figure 1 fuel pit fuel chute 1 is shown rising from a fuel pit (not shown) at an angle 01 from vertical. Reactor vessel fuel chute 2 is shown arising from a reactor vessel (not shown) at an angle 02 from vertical. In the arrangement shown in Figure 1,0i and 02 are equal and are approximately 20 degrees.

Fuel assemblies, (not shown) of approximately 550 hg weight, are to be transferred between chutes 1 and 2 which are not vertical. A hoist and trolley arrangement can accomplish the transfer with difficulty by coordinating movement of the trolley along the x axis (see coordinate axes 10) with hoist movement along axis y and filling of the transfer chamber. The coordination would require visual human control or complex computer control, both being undesirable.

The arrangement according to the present invention includes a shifting beam carriage having a plurality of beams 4 supporting a hoist box 6. The beams 4 are attached to hoist box 6 and to a base plate or series of base plates 11 by pivot pins 7. Hoist box 6 contains hoisting means (not shown) and may support a hoist tube 5.

Shifting of the carriage generally back and forth along the x axis is predetermined by certain design parameters to bring hoist tube 5 into alignment with respectively chute 1 and chute 2 and also to bring the end of hoist tube 5 into close proximity respectively to chutes 1 and 2.

Figure 1 defines symbols for angles and lengths used to design the shifting beam carriage. "CG" is the center of gravity of the carriage with a loaded fuel assembly.

It is noted that the hoist tube 5 may be inclined from the vertical by an angle (3 when the center of gravity 12 is midway between chutes 1 and 2, which may be the case when chute angles 0i and 02 are different from each other.

Figure 2 shows the shifting beam carriage in three positions. Position 13 shows hoist tube 5 in juxtaposition to fuel pit fuel chute 1, position 15 shows hoist tube 5 in juxtaposition to reactor vessel fuel chute 2, and position 14 is midway between the two.

In positions 13 and 15, hoist tube 5 can receive or dispense a fuel assembly into or out of the chute. In both positions hoist tube 5 is aligned with the chute at angle 01 or 02 so that the transfer of the fuel

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assembly therebetween is smoothly accomplished by a simple hoisting act.

Note that the center of gravity 12 of the carriage (with a fuel assembly within hoist tube 5) moves 5 approximately on a circle of relatively large radius providing for almost horizontal movement of the center of gravity 12. The movement ofthecarrige between positions 13 and 15 therefore does not require large forces, in fact there is only a need for 10 forces merely sufficient to overcome frictional resistance, principally in pins 7.

Figures 3,4 illustrate a preferred embodiment in which four beams 4 support a hoist box 6 via six pins 7. In the plan view of Figure 3, and in the profile view 15 of Figure4, means 16,17,18 for moving the carriage are shown. A transfer drive shaft 16 penetrates wall 3 and drives transfer chain 17. Transfer chain 17 extends between the drive shaft 16 and the idler pulley 18. At point 19, one leg of chain 17 is fixed to 20 hoist tube 5 so that, upon rotation of the drive shaft 16, hoist tube 5 is moved between the fuel pit fuel chutes 1 and 2.

Chain 17, shaft 16, and associated components need exert forces and withstand stresses merely 25 adequate to overcome frictional forces during transfer and need not be sufficiently strong to bear the fuel assembly weight.

Figure 3 also shows a winch drive shaft 20 with a winch chain 21 for control of a hoist located in hoist 30 box 6.

The rotary shafts 16 and 20 can be easily sealed at the sites of penetration through wall 3 to prevent escape of inerting gas or radiation. Outside the transfer chamber, these shafts will connect to drive 35 motors which are accessible for maintenance.

Claims

1. Afuel assembly transfer manipulatorfor

40 transferring fuel assemblies between upwardly open fuel chutes which are inclined relative to each other, said manipulator comprising a hoist box with hoisting means supported above said fuel chutes and having a downwardly projecting hoist tube (5) 45 supported for alignment with said fuel chutes (1,2) for transforming fuel elements therebetween, characterized in that said hoist box (6) is supported by pivot beams (4) having their low ends pivotally supported on a base and theirtop ends linked to said 50 hoist box (6), said pivot beams (4) being non-parallel and arranged at such an angle that said hoist tube (5) is in alignment with, and in juxtaposition to, said fuel chutes (1,2) at opposite pivot positions of said beams (4) and that means (16,17,18) are provided 55 for controlling pivoting of said beams (4).

2. A manipulator as claimed in claim 1, characterized inthatsaid means (16,17,18) for controlling beam pivoting includes a shaft (16) engaging a a drive chain (17) connected to said hoist tube (5).

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1983.

Published by The Patent Office, 25 Southampton Buildings, London, WC2A1 AY, from which copies may be obtained.